JPH04122938A - Positive type photoresist composition - Google Patents

Abstract

PURPOSE:To obtain the photoresist compsn. having a particularly wide latitude while maintaining a high resolving power without losing the sensitivity by incorporating an alkaline-soluble novolak resin having a specific degree of dispersion, 1, 2-quinone diazide compd. and a low-molecular compd. having phenolic hydroxyl groups at specific weight % of the novolak resin into the above compsn. CONSTITUTION:This cmpsn. contains the alkaline-soluble novolak resin having 1.5 o 4.0 ratio of a weight average mol. wt. and number average mol. wt., the 1, 2-quinone diazide compd. and the low-molecular compd. having 12 to 50C in total in one molecule and 2 o 8 pieces of the phenolic hydroxyl group in one molecule at 2 to 30wt.% of the novolak resin. The mol. wt. of the novolak resin refers to the value which is defined with a standard polystyrene as a reference value and is obtd. by gel permeation chromatography.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a specific alkali-soluble novolac resin, 1.2
-Relating to a positive photoresist composition sensitive to radiation such as ultraviolet rays, deep ultraviolet rays, X-rays, electron beams, molecular beams, γ-rays, synchrotron radiation, etc., containing a quinonediazide compound and a specific low-molecular component additive. More specifically, it is a positive type photoresist for microfabrication that has excellent development latitude, high sensitivity, and good resolution.

Typical fields of use are semiconductor manufacturing processes such as ICs, liquid crystals,
This is the manufacturing of circuit boards such as thermal heads, and other photo-op application processes.

"Prior Art" As a positive photoresist composition, a composition containing an alkali-soluble resin and a naphthoquinone cyacyto compound as a photosensitive material is generally used. For example, USP No. 3,666,473, 4,1
No. 15,128 and No. 4,173,470, etc., and the most typical composition is "novolac resin consisting of cresol-formaldehyde/trihydroxyhensiphenone-1,2-naphthoquinone siacitosulfonic acid ester". An example is Thompson's "Introduction to...
Microlithography J (L, F, Thomps
on rlntroduction to Mic
(ACS Publishing, No.
, No. 219, pp. 112-121).

Novolac resins as binders are particularly useful in this application because they can be dissolved in aqueous alkaline solutions without swelling and also provide high resistance to plasma etching, especially when the resulting image is used as an etching mask. It is. In addition, the naphthoquinone siacitate compound used as a photosensitive material itself acts as a dissolution inhibitor that reduces the alkali solubility of the novolac resin, but when it decomposes when exposed to light, it produces an alkali-soluble substance, rather than the alkali solubility of the novolac resin. It is unique in that it functions to increase solubility, and because of its large property change in response to light, it is particularly useful as a photosensitive material for positive photoresists.

From this point of view, many positive photoresists containing novolac resins and naphthoquinone cyacytophotosensitive materials have been developed and put into practical use, and have achieved satisfactory results in processing line widths of about 1 to 2 μm.

However, the degree of integration of integrated circuits is increasing, and
In the manufacture of semiconductor substrates such as SI, it has become necessary to process ultra-fine patterns having line widths of 1 μm or less. In such applications, a photoresist is required that has particularly high resolution, high pattern shape reproduction accuracy to accurately copy the shape of the exposure mask, and wide development latitude to ensure a dense and constant processing line width. In order to obtain even higher productivity, high sensitivity of the resist is also a necessary condition.

Conventionally, it has been considered advantageous to use a resist with a high γ value in order to improve resolution and obtain good image reproduction of pattern shapes.
Much effort has been made to develop resist compositions suitable for such purposes. There are an extremely large number of patents and reports disclosing such technology, and in particular, with regard to the technology of novolak resin, which is the main component of positive photoresists, many patent applications have been filed regarding its monomer composition, molecular weight distribution, synthesis method, etc. We have achieved certain results.

However, such high-resolution resists often have a common drawback of low sensitivity.

On the other hand, in order to increase sensitivity, a technique has been disclosed in which low-molecular-weight compounds having alkali-soluble groups are not added as dissolution promoters, but on the other hand, the development latitude becomes narrower.
In addition, new drawbacks such as damage to the pattern shape often occur.

Therefore, it has been desired to develop a resist with a wide development latitude, high sensitivity, and good resolution. Here, the development latitude can be expressed by the development time dependence or temperature dependence of the resist line width obtained by development.

``Problems to be Solved by the Present Invention'' Therefore, an object of the present invention is to obtain a positive-working photoresist composition having a particularly wide development latitude while maintaining high resolution and without loss of sensitivity.

"Means for Solving the Problems" The inventors of the present invention paid attention to the above-mentioned characteristics and, as a result of intensive study, found that the degree of dispersion of the novolak resin, that is, the weight average molecule t (
It has been found that the ratio of Mw) to number average molecular weight (Mn) (hereinafter referred to as dispersity) is important.

That is, the purpose of the present invention is to: (1) an alkali-soluble phenol novolak resin having a dispersity of 1.5 to 4.0; (2) a 1,2-quinonediazide compound; (2) a 1,2-quinone diazide compound; , a low molecular compound having a total number of carbon atoms in one molecule of 12 to 50 and 2 to 8 phenolic hydroxyl groups in one molecule. This was achieved by

However, the molecular weight of the novolac resin refers to a value obtained by gel verminion chromatography (hereinafter referred to as GPC) defined using standard polystyrene as a reference value.

Here, the relationship between the known technology and the present invention will be explained.

Attempts to improve the properties of resists by imparting a specific molecular weight distribution to novolak resins are already known. For example, JP-A-1-105243 describes that a novolac resin having a distribution such that the molecular weight range of 500 to 5000 is 30% or less is preferable. Also, JP-A-62-227144 and JP-A-62-227144,
No. 2044 indicates that there is a preferable range for the ratio of a specific molecular weight region in the molecular weight distribution. Furthermore, No. 60-97347 and No. 60-189739 contain novolak resins from which low molecular weight components have been fractionated, and No. 60-45238 in particular contains resins with a dispersity of 3 or less as used in the present invention. It is described that it is used.

Furthermore, the low molecular weight compound having an aromatic hydroxyl group that can be used in the present invention is usually used as a dissolution promoter for the purpose of improving sensitivity, and there are many examples of its addition to resist MA acid. Disclosed. However, when such a compound is added, film thinning in unexposed areas increases, resulting in deterioration of the shape of the resist. Furthermore, since the development speed is increased, the development latitude is also generally reduced. Therefore, structures of preferred compounds have been selected in such a way as to minimize these problems.

However, the effect of the present invention is a unique effect that is exhibited only when the novolak resin has a certain degree of dispersion and the above-mentioned low molecular compound is added thereto.

That is, when such a low-molecular-weight compound is bonded with the novolac resin specified in the present invention, the sensitivity of the resist is improved by the solubility promoting effect of the low-molecular-weight compound as expected. It also provides a wide development latitude.

It is not clear why such a unique effect occurs, but in any case, the resolution and development latitude obtained by this combination cannot be expected from either effect alone or from the effect of addition of acid. The present invention was made based on the discovery of this unique sheathing effect.

Aspects of the present invention will be explained in detail below.

The novolak resin used in the present acid product needs to have a relatively narrow molecular weight distribution. It is known that such a broadening of the molecular weight distribution of a polymer can generally be expressed by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn), that is, the Mw/Mn value (dispersity). The wider the distribution, the larger the value, and in the case of no distribution, the ratio value is 1.
becomes.

Novolac resins used in typical positive photoresists have a relatively wide molecular weight distribution, and many have a dispersity of 5 to 5, as typically shown in JP-A-62-172341. It's in the quiet part of 10. Also 5PIE proceedings rAdvances +n Re5
ist Techn.

1ogy and Processing VJ
Volume 920, page 349 suggests that a value between 4.55 and 6.75 gives a higher γ value than a value of 3°0.

In order for the novolac resin according to the present invention to exhibit such effects, the degree of dispersion must be different from these, and must be in the range of 1°5 to 4.0, more preferably 2.0 to 3.5. . If the degree of dispersion is too large, the wide development latitude that is the effect of the present invention cannot be obtained. Further, if this value is too small, a highly refined purification step is required to synthesize the novolac resin, which is unsuitable for practical use.

The novolac resin of the present invention preferably has an average molecular weight defined by Mw value in the range of 1,000 to 6,000, more preferably in the range of 2,000 to 4,500.

If the Mw value is too large, similarly to the above, the effect of the present invention of obtaining a wide development latitude cannot be obtained.

Various methods can be considered to produce a novolac resin having a small dispersity as in the present invention.

This can be obtained by selecting a specific phenolic monomer, selecting condensation reaction conditions, or fractionally precipitating a conventional novolac resin with a large degree of dispersion. In order to obtain the effects of the present invention, it may be manufactured using any of these methods.

Novolac resins can be obtained by polycondensing various phenols alone or a mixture of them with aldehydes such as formalin, but the phenols used here include phenol, p-cresol, m
-Cresol, 〇-Cresol, 2,3-dimethylphenol, 2゜4-dimethylphenol, 2,5-dimethylphenol, 2,6-dimethylphenol, 3,4-
Dimethylphenol, 3,5-dimethylphenol, 2
．． 3. 4-1-trimethylphenol, 2,3゜5-trimethylphenol, 3. 4. 5-) dimethylphenol, 2. 4. 5-) Dimethylphenol, methylenebisphenol, methylenebis p-cresol,
Resorcinol, catechol, 2-methylresorcinol, 4
-Methylresorcin, 0-chlorophenol, m-chlorophenol, p-chlorophenol, 2,3-dichlorophenol, p-methoxyphenol, m-methoxyphenol, p-butoxyphenol, 0-ethylphenol, m-ethylphenol , p-ethylphenol, 2,3-diethylphenol, 2,5-diethylphenol, p-isopropylphenol, p-tert-butylphenol, α-naphthol, β-naphthol, 4-phenylphenol, etc., singly or in combination. It can be used as a mixture. Among these, it is particularly preferable to use a mixture of alkylphenols such as cresol, dimethylphenol, and trimethylphenol. Moreover, monomethylolated products and dimethylolated products of these phenols can also be used as substituted phenols.

In addition to formalin, aldehydes include paraformaldehyde, acetaldehyde, benzaldehyde,
Hydroxybenzaldehyde, glyoxal, chloroacetaldehyde, dichloroacetaldehyde, bromoaldehyde, and the like can be used alone or in combination.

As the low molecular weight compound having a phenolic hydroxyl group constituting the present invention, those having a total number of carbon atoms in the molecule of 12 to 50 and a total number of phenolic hydroxyl groups of 2 to 8 are used.

Among such compounds, compounds that increase the alkali dissolution rate of the novolak resin when added to the novolak resin used in the present invention are particularly desirable. Furthermore, if the compound has 51 or more carbon atoms, the effects of the present invention will be significantly reduced.

Moreover, if it is less than 11, new drawbacks such as a decrease in heat resistance occur. In order to bring out the effects of the present invention,
It is necessary to have at least 2 hydroxyl groups in the molecule, but if the number is 9 or more, the effect of improving development latitude is lost.

The amount of this low molecular compound added is preferably 2 to 30% by weight, more preferably 5 to 25% by weight based on the novolac resin.
Weight%. If the amount added exceeds 30% by weight, a new drawback occurs in that the pattern is deformed during development.

This effect can be obtained by using any low-molecular compound as long as it satisfies the above structural requirements, but especially the low-molecular component of the novolak resin itself as shown in general formula (1) is Those with different structures are preferred. As such, for example, the following general formula (
Among the compounds described in 2) to (9), those having a structure that satisfies the requirements of the present invention are identified as compounds that are particularly likely to exhibit this effect. Although structures other than this can be used in the present invention, for example, in the case of a compound described by general formula (1), although the effect is there, it is small compared to the above-mentioned one.

Furthermore, polyhydroxy aromatic compounds that can serve as intermediate raw materials (skeleton) for photosensitizers described later can also be used for this purpose. However, in order to exhibit this effect most effectively, it is desirable to select a compound having a smaller ratio of (hydroxyl group/total number of carbon atoms) in the molecule than the photosensitizer skeleton compound actually used in the present invention.

(R1)a (R2)b Formula - (4) (R2)f (R3)! In the above general formula, each symbol represents the following.

R1-R4 may be the same or different, and are a halogen atom, a lower alkyl group, an alkoxy group, an acyl group, or an acyloxy group.

R5, R6: may be the same or different, hydrogen atom, lower alkyl group, lower haloalkyl group.

R7: hydrogen atom, halogen atom, lower alkyl group,
Alkoxy group, acyl group, acyloxy group.

R8-R10: which may be the same or different, hydrogen atom, halogen atom, hydroxyl group, lower alkyl group, alkoxy group, acyl group, acyloxy group.

a=d: 0 or an integer from 1 to 3.

~n: An integer from 1 to 3.

e~8:0 or an integer from 1 to 2.

p: An integer from 1 to 3.

h: 0 or an integer from 1 to (4-p).

q: Integer from 3 to 8.

``: An integer from 1 to 3.

s: 0 or an integer from 1 to 4, general formula (1)
represents a mixture of these things.

A: Hydrogen atom, hydroxyl group.

X: methylene group, lower alkyl-substituted methylene group, haromethylene group, haloalkylmethylene group.

Y: methylene group, lower alkyl-substituted methylene group, hengelidene group, substituted hengelidene group, carbon Fi2 or more 8
straight-chain or branched alkylene groups, substituted alkylene groups thereof, and oxaalkylene groups.

Z: Single bond, oxymethylene group.

Furthermore, the 1,2-naphthoquinone cyacyto compounds used in the present invention include 1,2-naphthoquinone cyato-5-sulfonic acid, 1,2-naphthoquinone cyato-4-sulfonic acid, or 1,2-naphthoquinone cyato-5-sulfonic acid. Esters of cycloquinone cyadito-4-sulfonic acid and polyhydroxy aromatic compounds are used.

As the polyhydroxy aromatic compound, for example, 2,3
．． 4-) Lihydroxybenzophenone, 2.4.4'-
1-lihydroxyhenzophenone, 2,4.6-lihydroxyhenzophenone, 2.3.4.

4゛-Tetrahydroxyhenzophenone, 2,2゜4.
4+-tetrahydroxyhenzophenone, 2,4.6.
Polyhydroxyhensiphenone neck, such as 3',4',5'-hexahydroxybenzophenone, 2,3,4.3',4',5'-hexahydroxyhensiphenone, 2,3.4- ) Lihydroxyacetophenone, 2.3
．． Polyhydroxyphenylalkyl ketones such as 4-1-lihydroxyphenylhexyl ketone, bis(2,4-
Bis((poly)hydroxyphenyl)alkanes such as dihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)methane, bis(2,4-dihydroxyphenyl)bronoN-1, 3,4.5 -) Polyhydroxybenzoic acid esters such as propyl lihydroxybenzoate, phenyl 3,4.5-1 lyhydroxybenzoate, bis(2,3,4-trihydroxyhenzoyl)methane, bis(2,3,4 - Trihythrogyshihenzoyl)
Bis(polyhydroxybenzoyl) alkanes or bis(polyhydroxybenzoyl)aryls such as Hensen,
Alkylene group di(bonohydroxyhenzoate) such as ethylene glycol di(3,5-dihydroxybenzoate), 3.5.3',5' biphenyl tetrol, 2.4.2',4'-biphenyl tetrol ,
2.4.6.3',5'-biphenylpentol,
2.4.6.2 Polyhydroxybiphenyls such as 4', 4', 6'-biphenylhexol, 4,4Z3+
Z41+-tetrahydroxy-3,5,3',5'-tetramethyltriphenylmethane, 4.4',2'1,
311, 411-pentahydroxy-3,5,3',
5'-tetramethyltriphenylmethane, 2,3,4,
Polyhydroxytriphenylmethanes such as 231, 41, 311, 411-octahydroxy-5,5-diacetyltriphenylmethane, 3,3.3', 3'-
Tetramethyl-1,1'-spirobiindane-5,6
゜5+,6''-tetrol, 3,3.3',3'-tetramethyl-1,1''-spirobeindan-5,6,7
,5261,7+-hexol,3.3.3',3
'-Tetramethyl-1,1'-spirobiindane-4
,5,641,51,61-hexol,3,3.3
',3'-tetramethyl-1,1'-spirobiindane-4,5,6,5',6',7'-hexol and other polyhydroxyspirobiindanes, 3,3-bis(
3,4-dihydroxyphenyl)phthalide, 3,3-bis(2,3,4-)dihydroxyphenyl)phthalide,
Polyhydroxyphthalides such as 3',4',5',6'-tetrahydroxybiro[phthalide-3,9'-xanthine], 2-(3,4-dihydroxyphenyl)-3,5, 7-trihydroxybenzobilane, 2-(
3,4,5-1lihydroxyphenyl)-3,5゜7-
Dolihydroxybenzopyran, 2-(3,4-dihydroxyphenyl)-3-(3,4,5-)lihydroxyhenzoyloxy)-5,7-dihydroxyhenzopyran, 2-(3,4 ,5-)dihydroxyphenyl) −
3-(3,4,5-)lyhydroxyhenzoyloxy)
-Polyhydroxyhenzobilane neck with 5,7-dihydroxyhenzopyran, 2.4.4-)limethyl-2-(
2',4'-dihydroxyphenyl)-7-hydroxychroman, 2,4.4-trimethyl-2-(2',3'
, 4'-)lihydroxyphenyl)-7,8-dihydroxychroman, 2.4.4-trimethyl-2-(2',
4',6'-)lihydroxyphenyl)-5,7-
Polyhydroxyphenylchromans such as dihydroxychroman, 2,6-bis(2,3,4-)dihydroxyhensyl)-4-methylphenol, 2,6-bis(2
, 4-dihydroxybenzyl〉-4-methylphenol, 2,6-bis(5-chloro-2,4-dihydroxybenzyl)-4-methylphenol, 2,6-bis(2,
4-dihydroxyhensyl)-4-methylphenol,
2,6-bis(2,4-dihydroxyhensyl)-4-
Methylphenol, 2,6-bis(2-hydroxyhensyl)-4-methylphenol, 2,6-bis(2,4
-dihydroxycurondyl)-4-methylphenol,
2,6-bis(2,4-dihydroxyhensyl)-4-
Methylphenol, 2,6-bis(2,3,4-)dihydroxyhensyl)-4-methylphenol, 2,6-
Bis(2,3,4-trihydroxyhensyl)-4-methylphenol, 2,6-bis(2,4,6-trihydroxyhensyl)-4-methylphenol, 2,6-bis(2- acetyl-3,4,5-)dihydroxyhensyl)-4-methylphenol, 2,4.6-)lis(2
,3,4-)dihydroxyhensyl)phenol,2,
6-bis(3,5-dimethyl-4-hydroxybenzyl)-4-methylphenol, 2,4°6-tris(3,
5-dimethyl-4-hydroxyhensyl)-4-methylphenol, 4,6-bis(3,5-dimethyl-4-hydroxybenzyl)pyrogallol, 2,6-bis(3,
Hydroxyhenzylphenols such as 5-dimethyl-4-hydroxybenzyl)-4-methylphenol, 2,6-bis(3,5-dimethyl-4-hydroxybenzyl)phloroglucinol, or quercetin, rutin, etc. Flavono pigments and the like, furthermore, low-nuclear forms of novolak or analogs thereof can be used.

Further, polymers containing aromatic hydroxyl groups such as acetone pyrogallol condensation resin and polyvinylphenol can be used instead of these low molecular weight compounds. It is also possible to substitute an appropriate amount of the hydroxyl group of the novolac of the present invention with quinonediazide so that it can function as a photosensitive material or as a binder. Among these, those having a structure including a moiety having two or more aromatic hydroxyl groups on the same aromatic ring and having three or more hydroxyl groups in total are particularly preferred.

The photosensitive material contains the above-mentioned polyhydroxy compound with 1.2-
Although it is a compound substituted with a naphthoquinonediazide group, a mixture of isomers having different degrees of substitution is generally used. However, in order to exhibit the effects of the present invention, it is not preferable to mix in isomers with a low degree of substitution. To be more specific, the total of isomers in which all hydroxyl groups have been substituted and isomers in which only one hydroxyl group remains unsubstituted is 80% of the entire photosensitive material.
It is necessary to use at least 90% by weight, more preferably at least 90% by weight.

The ratio of the photosensitive material and the alkali-soluble novolac resin used in the present invention is 5 to 50 parts by weight, preferably 10 to 30 MM parts, per 100 parts by weight of the novolak resin. If this usage ratio is less than 5 parts by weight, the residual film rate will be significantly reduced, and if it exceeds 50 parts by weight, sensitivity and solubility in solvents will be reduced.

Examples of solvents for dissolving the photosensitive material and alkali-soluble novolac resin of the present invention include ketones such as methyl ethyl ketone and cyclohexanone, alcohol ethers such as ethylene glycol monomethyl ether and ethylene glycol monoethyl ether, and ethers such as dioxane and ethylene glycol dimethyl ether. , cellosolve esters such as methyl cellosolve acetate and ethyl cellosolve acetate, fatty acid esters such as butyl acetate, methyl lactate, and ethyl lactate, 1.1.2-) halogenated hydrocarbons such as dichloroethylene, dimethyl acetamide, Examples include highly polar solvents such as N-methylpyrrolidone, dimethylformamide, and dimethylsulfoxide. These solvents can be used alone or in combination.

A dye, a plasticizer, an adhesion aid, a surfactant, etc. can be added to the sieved acid material for positive photoresists of the present invention, if necessary. Specific examples include dyes such as methyl violet, crystal violet, and malachite green, plasticizers such as stearic acid, acetal resin, phenoxy resin, alkyd resin, and epoxy resin, and adhesives such as hexamethyldisilazane and chloromethylsilane. There are auxiliary agents and surfactants such as nonylphenoxy poly(ethyleneoxy)ethanol and octylphenoxypoly(ethyleneoxy)ethanol.

In particular, dyes containing alkali-soluble groups such as aromatic hydroxyl groups and carboxylic acid groups in the molecule, such as curcumin, are particularly advantageously used, but when such compounds are added, the present invention It is desirable to adjust the amount of small molecule solubility enhancer accordingly to obtain optimal performance.

The above positive photoresist composition is applied onto substrates such as those used in the manufacture of precision integrated circuit devices (e.g., silicon/silicon dioxide coating), glass, ceramics, metal, etc. by an appropriate coating method such as a spinner coater. 0.
After coating to a thickness of 5 to 3 μm, a good resist can be obtained by exposing to light through a predetermined mask and developing. For the purpose of improving coating properties, it is also preferable to add a surfactant having a fluorine substituent group, a silicon-containing group, etc. to lower the surface tension.

The developing solution for the positive photoresist composition of the present invention includes sodium hydroxide, hydroxide, sodium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, inorganic alkalis such as aqueous ammonia, ethylamine, n-propyl Primary amines such as amines, diethylamine, di-n
- tertiary amines such as butylamine, triethylamine,
Tertiary amines such as methyldiethylamine, alcohol amines such as dimethylethanolamine and triethanolamine, quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide, cyclic amines such as pyrrole and piperidine. Aqueous solutions of alkalis such as can be used. Furthermore, appropriate amounts of alcohols, surfactants, aromatic hydroxyl group-containing compounds, etc. may be added to the aqueous solution of the alkali. Among these, it is most preferable to use tetraammonium hydroxide.

"Effect of the invention" Positive photoresist of the present invention)! Acids have excellent resolution,
It is characterized by high sensitivity and wide development latitude. Therefore, it is most suitable for mass production of semiconductor substrates having ultra-fine circuits.

"Examples" The present invention will be explained below with reference to Examples, but the aspects of the present invention should not be limited only to these Examples.

Synthesis Example 1 Synthesis examples of the novolak resin (b) according to the present invention and the novolak resin (a) for comparison are shown below.

(1) Synthesis of novolac resin (a) m-cresol 45g, p-cresol 55g, 37%
Formalin aqueous solution 44.9g and oxalic acid dihydrate 0.0
5g was placed in a three-bottle flask equipped with a stirrer, reflux condenser, and thermometer, and the temperature was raised to 100°C while stirring.
The reaction was allowed to proceed for 7 hours. After repulsion, the reactor was cooled to room temperature, the reflux condenser was removed, and the pressure was reduced to 30% Hg.

The temperature was then gradually raised to 150°C to remove water and unreacted monomers. When the obtained novolac resin was analyzed by GPC using a polystyrene standard, the Mw was 2310 and the dispersity was 5.54. This was designated as novolac resin (a).

(2) Synthesis of novolac resin (b) Take 54 g of the above novolac resin (a) and add 500 m1
of MEK, then 2000 ml of cyclohexane was added and heated to 60° C. with stirring. This solution was allowed to stand at room temperature for 16 hours to obtain a precipitate. This precipitate was collected, filtered, and dried in a vacuum oven at 50°C to obtain about 18 g of novolac resin (b).

When this is analyzed using GPC, Mw is 3540° The degree of dispersion was 305.

Synthesis Example 2 Synthesis examples of other novolak resins (C) (d) according to the present invention and novolak resin (e) for comparison are shown below.

(3) Synthesis of novolak resin (c) m-cresol eog, p-cresol 28g, 2.6
-Pishitroxymethyl p-cresol 31.2g, 3
22.4 g of a 7% formalin aqueous solution was placed in a three-bottle flask equipped with a stirrer, a reflux condenser, and a thermometer.
The mixture was stirred while heating in a 10°C oil bath. When the internal temperature reached 90° C., 1.30 g of oxalic acid dihydrate was added.

Thereafter, the reaction was continued under reflux for 15 hours, and the temperature of the oil bath was further raised to 200° C., and water and unreacted monomers were removed under reduced pressure with the reflux condenser removed. When the obtained novolak resin was analyzed by GPC, the Mw was 3560 and the dispersity was 3.
．． It was 75.

(4) Synthesis of novolac resin (d) In a 500 ml Kherbourg flask, 50 g of the above novolac resin (c) was dissolved in a mixed solvent of 150 g of methanol and 25 g of ethyl cellosolve acetate (ECA), and then When 100 g of pure water was added with stirring, the liquid became cloudy. This was left at room temperature for 30 minutes to obtain two separated layers. After removing the upper layer by decantation, the solvent was removed by distillation under reduced pressure to obtain a solid novolak resin. Mw was 4280 and dispersity was 3.36.

(5) Synthesis of novolak resin (e) m-cresol 60g, p-cresol 40g, 2.6
-Pishitroxymethyl p-cresol 15.6g, 3
Pour 40.7 g of a 7% formalin aqueous solution into a three-bottle flask equipped with a stirrer, reflux condenser, and thermometer, and then add 2.60 g of Cucumber W! Dodecahydrate was added and stirred while heating in a 110°C oil bath. The reaction was continued under reflux for 18 hours, and the temperature of the oil bath was further raised to 200°C, and water and unreacted monomers were removed under reduced pressure with the reflux condenser removed. When the obtained novolak resin was analyzed by GPC, it was found that Mw
was 6360, and the degree of dispersion was 4.68.

Synthesis Example 3 Below, still another novolak resin (f) (g
) and a synthesis example of novolac resin (h) for comparison.

(6) Synthesis of novolak resin (f) m-cresol 20g, p-cresol 30g, 2.3
- 22.6 g of dimethylphenol, 4664 g of 2,6-pishydroxymethyl p-cresol and 500 g of EC
The mixture was mixed with A and charged into a three-hole flask equipped with a stirrer, a reflux condenser, and a thermometer. Next, 6.8 g of a 37% formalin aqueous solution was added and stirred while heating in a 110° C. oil bath. When the internal temperature reached 90° C., 5.4 g of oxalic acid dihydrate was added. Thereafter, the reaction was continued by keeping the temperature of the oil bath at 110° C. for 18 hours, and after cooling the reaction product, it was poured into a large amount of water to collect the precipitated novolac resin and dry it.

The obtained novolac resin has a Mw of 2320 and a dispersity of 2.
．． It was 05.

(7) Synthesis of novolak resin (g) m-cresol 20g, p-cresol 45g 12.3
- 22.6 g of dimethylphenol, 23.2 g of 2,6-bishydroxymethyl p-cresol and 150 g of EC
The mixture was mixed with A and charged into a three-hole flask equipped with a stirrer, a reflux condenser, and a thermometer. Next, 31.8 g of a 37% formalin aqueous solution was added, and the mixture was stirred while heating in an oil bath at 110.degree. When the internal temperature reaches 90℃, 10.2
g of 81112 hydrate was added. Thereafter, the reaction was continued by keeping the temperature of the oil bath at 110° C. for 18 hours, and after cooling the reaction product, it was poured into a large amount of water to collect the precipitated novolac resin and dry it. The obtained novolac resin had an Mw of 4720 and a dispersity of 3.32.

(8) Synthesis of novolak resin (h) m-cresol 20g, p-cresol 55g, 2.3
-dimethylphenol22. 6g, 2. 7.7 g of 6-bishydroxymethyl p-cresol was charged into a three-hole flask equipped with a stirrer, a reflux condenser, and a thermometer. Next, 40.6 g of 37% formalin liquid
was added and stirred while heating in a 110°C oil bath. When the internal temperature reached 90° C., 2.3 g of oxalic acid dihydrate was added. Thereafter, the reaction was continued while keeping the temperature of the oil bath at 110° C. for 18 hours, and then the reflux condenser was removed and vacuum distillation was performed at 200° C. to remove unreacted monomers. After 200 g of ECA was added and the reaction mixture was cooled, it was poured into a large amount of water to collect the precipitated novolac resin and dried. The obtained novolak resin had an Mw of 8690 and a dispersity of 6.25.

Synthesis Example 4 Below, still another novolak resin (j) (J
) is shown below.

(8) Synthesis of novolak resin (1) p-cresol 30g, o-cresol 14g, 2.3
- 50 g of dimethylphenol, 2. 3. 5-trimethylphenol 20g, 2,6-dimethylphenol 4
．． 9 g was mixed with 50 g of diethylene glycol monomethyl ether and charged into a three-hole flask equipped with a stirrer, reflux condenser, and thermometer. Next, 85 g of a 37% formalin aqueous solution was added, and the mixture was stirred while being heated in an oil bath at 110°C. When the internal temperature reached 90° C., 6.2 g of oxalic acid dihydrate was added. Thereafter, the reaction was continued while keeping the temperature of the oil bath at 130°C for 18 hours, and then the reflux condenser was removed and vacuum distillation was performed at 200°C to remove unreacted monomers. The obtained novolak resin had an Mw of 3230 and a dispersity of 2.75.

(9) Synthesis of novolac resin (j) In a 500 ml Kerbourg flask, 50 g of the above novolak resin (i) was dissolved in a mixed solvent of 100 g of methanol and 50 g of ethyl cellosolve acetate (ECA), Next, when 50 g of pure water was added with stirring, the liquid became cloudy. This was left at room temperature for 30 minutes to obtain two separated layers. After removing the upper layer by decantation,
The solvent was removed by distillation under reduced pressure to obtain a solid novolac resin.

Mw was 4320 and dispersity was 3.68.

Synthesis Example 5 A synthesis example of still another novolac resin (k) according to the present invention is shown below.

(10) Synthesis of novolac resin (k) m-cresol 60g, p-cresol 40g, 37%
Formalin aqueous solution 48.6g and oxalic acid dihydrate 0.0
5g was placed in a three-bottle flask equipped with a stirrer, reflux condenser, and thermometer, and the temperature was raised to 100°C while stirring.
The reaction was allowed to proceed for 7 hours. After repulsion, the reactor was cooled to room temperature, the reflux condenser was removed, and the pressure was reduced to 30 Hg.

The temperature was then gradually raised to 150°C to remove water and unreacted monomers. When the obtained novolac resin was analyzed by GPC using a polystyrene standard, the Mw was 7350 and the dispersity was 7.86.

10 g of this novolac resin was dissolved in 500 ml of THE, and the mixture was applied to a preparative GPC column TSK-GEL, G-20.
A GPC device equipped with two batteries, 8 on 00H and 6 (manufactured by Tosoh) on G4000H, was charged. THFli as solution M: flowed at a flow rate of 5 m1/min, Mw (II = 6
The range of 000 to 8000 was fractionated and collected. The novolac resin obtained by distilling off the solvent was designated as resin (k). GPC
When analyzed, the Mw was 7260 and the degree of dispersion was 2.55.

Synthesis Example 6 Next, formula (1) is used as an example of a low molecular compound.
Novolac resin oligomer (m), (n) corresponding to
Examples of synthesis and examples of synthesis of novolac resin oligomer (0) that do not fall under the present invention are shown below.

(11) Synthesis of novolac oligomer (m) 30 g of m-cresol, 70 g of p-cresol, 41.0 g of 37% formalin aqueous solution, and 0.05 g of Cucumber Wli dihydrate
The mixture was charged into a three-bottle flask equipped with a stirrer, a reflux condenser, and a thermometer, and the temperature was raised to 100° C. while stirring, and the mixture was reacted for 7 hours. After repulsion, the reactor was cooled to room temperature, the reflux condenser was removed, and the pressure was reduced to 30 mmHg.

The temperature was then gradually raised to 150°C to remove water and unreacted monomers. When the obtained novolak oligomer was analyzed by GPC using a polystyrene standard, it was found to be a mixture mainly composed of dinuclear to tetranuclear bodies.

(12) Synthesis of novolak oligomer (n) 2. 57.7 g of 6-pishydroxymethyl p-cresol, 69.5 g of m-cresol and 0.05 g of N acid dihydrate were added using a stirrer, a reflux condenser, and a temperature The mixture was placed in a three-bottle flask equipped with a meter, heated to 100° C. with stirring, and reacted for 7 hours.

After repulsion, cool to room temperature, remove the reflux condenser, and incubate for 30 minutes.
The pressure was reduced to mmHg.

The temperature was then gradually raised to 150°C to remove water and unreacted monomers. When the obtained novolak oligomer was analyzed by GPC using a polystyrene standard, it was found to be a mixture mainly composed of dinuclear to hexanuclear bodies.

(13) Synthesis of novolac oligomer (0) 77.3 g of 2.6-bishydroxymethyl p-cresol, 50 g of m-cresol and 0.05 g of oxalic acid dihydrate were mixed in a stirrer,
The mixture was placed in a three-bottle flask equipped with a reflux condenser and a thermometer, heated to 100° C. with stirring, and reacted for 18 hours. After repulsion, the reactor was cooled to room temperature, the reflux condenser was removed, and the pressure was reduced to 301 Hg.

The temperature was then gradually raised to 150°C to remove water and unreacted monomers. When the obtained novolac oligomer was analyzed by GPC using a polystyrene standard, it was found to be a mixture mainly composed of dinuclear to dodecanuclear bodies, with an average of about octanuclear bodies (carbon number = 63).

Synthesis Example 7 (14) Synthesis of photosensitive material (A) 2, 3. 4. 10 g of 4'-tetrahydroxybenzophenone, 43 g of 1,2-naphthoquinone cyacyto-5-sulfonyl chloride and 400 ml of γ-butyrolactone
Three of these were placed in a flask and uniformly dissolved. Next, a mixed solution of triethylamine/acetone=17 g/40 ml was gradually added dropwise, and the mixture was reacted at 25° C. for 3 hours. The reaction mixture was poured into a 1% aqueous hydrochloric acid solution (10,100 O), and the resulting precipitate was filtered off, washed with water and methanol, and dried (40°C) to recover a photosensitive material (A).

When the product was analyzed by high performance liquid chromatography (HPLC), the peak area ratio on the chart detected by the absorbance at 254 nm showed that the tetrasubstituted ester was 89
It was a mixture consisting of 5% trisubstituted ester and the remainder other low substituted esters.

(15) Synthesis of photosensitive material (B) 4, 4. 4', 4', -tetramethyl-2
,2'-subirobichroman-6,7,6', 7'-
Tetrol 10g, 1,2-naphthoquinonediazide-5
-34.5 g of sulfonyl chloride and 500 g of dioxane
Three samples of ml were placed in a flask and uniformly dissolved.

Next, triethylamine/dioxane = 13.7g/
50 ml of the mixed solution was gradually added dropwise and reacted at 25°C for 3 hours. The reaction mixture was dissolved in 1500ml of 1% aqueous hydrochloric acid solution.
The resulting precipitate was filtered, washed with water and methanol, and dried (40°C) to recover a photosensitive material (B).

When the product was analyzed by HPLC in the same manner as above, it was found to be a mixture consisting of 93% 4-substituted ester and the remainder other low-substituted esters.

(]6) Synthesis of photosensitive material (C) 3, 3. 3', 3'-tetramethyl-], 1'
-spirobiindane-5,6,7,5', 6',
10 g of 7'-hexol, 34.5 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 500 ml of acetone were placed in three flasks and uniformly dissolved.

Next, triethylamine/acetone = 13°7g150
A mixed solution of m1 was gradually added dropwise, and the mixture was reacted at 25° C. for 3 hours. The reaction mixture was poured into 1500 ml of a 1% aqueous hydrochloric acid solution, and the resulting precipitate was filtered off, washed with water and methanol, and dried (40°C) to recover a photosensitive material (C).

When the product was analyzed by HPLC, it was found to be a mixture consisting of 96% 4-substituted ester and the remainder other low-substituted esters.

(17) Synthesis of photosensitive material (D) 10 g of 2.6-bis(3,5-dimethyl-4-hydroxybenzyl)p-cresol, 31.3 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride and 300 ml of acetone were added. The mixture was placed in three flasks and uniformly dissolved. Then triethylamine/acetone = 12.4g/3
0 ml of the mixed solution was gradually added dropwise and reacted at 25° C. for 15 hours.

The reaction mixture was poured into 1500 ml of 1% aqueous hydrochloric acid solution, and the resulting precipitate was filtered off, washed with water and methanol, and dried (4
0° C.), and the photosensitive material (D) was collected.

When the product was analyzed by HPLC, it was found to be a mixture consisting of 83% tri-substituted ester, 12% di-substituted ester, and the remainder other low-substituted substances.

(18) Synthesis of photosensitive material (E) 2. 10 g of 6-bis(3,5-dimethyl-4-hydroxyhensyl)pyrogallol, 31.8 g of 1,2-naphthoquinone cyato-5-sulfonyl chloride and 300 ml of acetone. The mixture was placed in three flasks and uniformly dissolved.

Then triethylamine/acetone = 12.6g/30
A mixed solution of m1 was gradually added dropwise, and the mixture was reacted at 25° C. for 15 hours. The reaction mixture was poured into 1500 ml of a 1% aqueous hydrochloric acid solution, and the resulting precipitate was filtered off, washed with water and methanol, and dried (40°C) to recover a photosensitive material (E).

When the product was analyzed by HPLC, it was found to be a mixture consisting of 93% 5It-converted ester and the remainder other low-substituted products.

(19)! Synthesis of optical substance (F) 2.6-bis(2,3,4-)lyhydroxybenzyl)
10 g of p-cresol, 52.4 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 500 ml of γ-butyrolactone were placed in three flasks and uniformly dissolved. Then triethylamine/acetone = 20
．． Gradually drop a mixture of 7g/30ml and heat at 25°C.
The reaction was allowed to proceed for 5 hours. The reaction mixture was diluted with 1% aqueous hydrochloric acid solution at 150%
The resulting precipitate was filtered, washed with water and methanol, and dried (40°C) to recover a photosensitive material (F).

Analysis of the product by HPLC revealed that there were 4 7-substituted esters.
8%, 44% hexasubstituted ester, and the remainder was a mixture consisting of other low substituted esters.

(20)! Synthesis of light objects (G) 2, 3. 4. 10 g of 4'-tetrahydroxybenzophenone, 29.7 g of 1,2-naphthoquinonediazide-5-sulfonyl chloride, and 400 ml of dioxane were charged into three flasks and uniformly dissolved. Next, a mixed solution of triethylamine/dioxane=11°8g/40ml was gradually added dropwise, and the mixture was reacted at 25°C for 3 hours. The reaction mixture was poured into a 1% aqueous hydrochloric acid solution (10,100 O), and the resulting precipitate was filtered off, washed with water, and dried (40° C.) to recover a photosensitive material (G).

Analysis of the product by high performance liquid chromatography (HPLC) revealed that 43% was 4-substituted esters, 24% was 3-substituted esters, 12% was 2-substituted esters, and the remaining 21% was other low-substituted products and unreacted tetrahydroxy. It was a mixture consisting of benzophenone.

Examples of resists of the present invention and comparative resists prepared by combining the novolatile resin produced in the above synthesis example with a predetermined low-molecular compound are shown below.

First, specific examples of the low molecular weight compounds used in this example are shown using the following abbreviations.

Compound-1: -In formula (2), a-d=o, D=
2. Compound of 2'-isopropylene.

Compound-2 - In formula (2), a-d=1, R1
~R4=methyl group, D=2.2'-isopropylene compound.

Compound-32-In formula (3), a-c=:01R
4-R6 = methyl group, A = hydroxyl group, r = 1 compound.

Compound-4: -4,6-bis( in formula (4))
3,5-dimethyl-4-hydroxyhensyl)picogallol.

Compound-52-2,6-bis( in formula (4))
2,3,4-)lihydroxyhenzyl)-p-cresol.

Compound-6: -2,6-bis( in formula (4))
2-Hydroxy-5-methylbenzyl)-p-cresol.

Compound *-7: - p-cresol dimer compound -8 in formula (4) - 2,4゜5-tris(3,5-dimethyl-4-hydroxyhensyl in formula (5)) )−
1,3,5-)lyhydroxybenzene.

Compound-92-2,4゜5-tris(2-hydroxyhensyl)-1゜3.5-)rimethoxyhenzene in formula (5).

Compound-10=-2,4°6 in formula (6).
3',5'-pentahydroxybiphenyl.

Compound-11=-bis(3,5 in formula (6)
-dimethyl-4-hydroxyphenyl)-2,4-dihydroxyphenylmethane.

Compound-12-Nordihydroguaiaretic acid in formula (6).

Compound-132-2,8°14 in formula (7)
．． 20-tetramethylpentacyclo [19.3.1.1
”・7.19・13,115・19] Octacosa-1 (
25), 3, 5.7 (28), 9, 11.13 (27)
.

] 5,17.19(26), 21.23-F decaene-4,6,10,12,16,1B, 22.24-ophthol.

Compound-14=-1-(4-hydroxyphenyl)-1,3,3-)damethyl-5,6 in formula (8)
-Dihydrocoxyindan.

Compound-152-2-(3,5 in formula (9)
-dimethyl-4-hydroxyphenyl)-3,5,7-
Trihydroxybenzopyran.

In addition, examples of low molecular weight compounds that were tested for comparison and do not fall under the present invention are shown below.

Compound-16 = Phloroglucinol compound-17: 4-phenylphenol compound-18
2 - In formula (2), a-d=l, R1 to R4=isopropyl group, D=nidimethylmethylene compound (total carbon number=55) Compound-19: 2,4.6-) Lis( 2,3゜4-
trich F゛roxy-5-benzoyl)-1゜3.5-)
Lihydroxybenzene (total number of hydroxyl groups = 12) Compound-202 - In formula (6), bis(2°3.
4-) hydroxy-5-acetyl phenol) -3,
4,5-)dihydroxyphenylmethane (total number of hydroxyl groups =
9) Example 1 Novolac resins (a) to (obtained in Synthesis Examples 1 to 5 above)
k) to 5 g, and photosensitive material (A) obtained in Synthesis Example 7 to 1.
10g, and further mixed the above-mentioned low-molecular compound-3 with the powder listed in Table-1, dissolved in 18g of ethyl lactate, and added 0.2μ
A photoresist composition was prepared by filtration using a microfilter. This photoresist was applied onto a silicon wafer using a spinner and dried on a vacuum suction hot plate at 90° C. for 60 seconds to obtain a resist film with a thickness of 1.2 μm. After exposing this film using a reduction projection exposure device (FPA-1550M-m manufactured by Canon) e,
Heat for 90 seconds on a vacuum adsorption hot plate at 0°C,
, 38% aqueous solution of tetramethylammonium hydroxide for 1 minute, washed with water for 30 seconds, and dried. The resist pattern of the silicon wafer thus obtained was observed with a scanning electron microscope, and the resist was evaluated.

The results are shown in Table-1.

Sensitivity is 0. It was defined as the exposure amount that reproduces a 7 μm mask pattern.

Furthermore, in order to evaluate the development latitude of each sample, the same evaluation was performed by changing the development time to 20 seconds and 901 seconds. The ratio of the sensitivities defined above between the two was used as an index of development latitude. This value is 1.0
The closer it is to , the wider the development latitude and the more desirable the result.

The resolution represents the limit resolution at an exposure amount that reproduces a mask pattern of 0178 m.

Heat resistance was determined by baking a silicon wafer on which a resist pattern was formed on a hot plate for 4 minutes, and showing the temperature at which the pattern did not deform.

Example 2 Novolac resin (b) obtained in Synthesis Example 1.2.4 above
(d) (j) was added to 5 g, and the photosensitive material (B
) to (G) as 1. 10g, and further the above low molecular compound-3
were mixed in the amounts listed in Table 2, and this was mixed with 18g of ethyl lactate.
A photoresist composition was prepared by dissolving the photoresist composition in water and filtering it using a 0.2 μm microfilter. Example 1
It was evaluated in the same manner. The results obtained are shown in Table-2.

Example 3 5 g of the novolac resin (d) obtained in Synthesis Example 2 above was added to the photosensitive materials (A) to (C,) obtained in Reference Example 7, and further the low molecular weight compounds -1 to 20, or the above. Table 3 shows the novolac resin oligomers (m) to (0) obtained in Reference Example 6.
Mix in the amount described in , dissolve this in 18 g of ethyl lactate, and add 0. A photoresist composition was prepared by filtration using a 2 μm microfilter. This was evaluated in the same manner as in Example 1.

The results obtained are summarized in Table 3.

As described above, it can be seen that the resist samples that meet the requirements of the present invention exhibit high resolution without a significant decrease in sensitivity, and all have better development latitude than the comparative samples.

-Procedure Nakayama-r1 day-1= (spontaneous)) February 6, 1991

Claims (3)

[Claims] (1) The ratio of weight average molecular weight to number average molecular weight is 1.5 to 4
．． an alkali-soluble phenolic novolak resin having a (2) 1,2-quinonediazide compound, (3) 2 to 30% by weight of 1 to the novolak resin;
The total number of carbon atoms in the molecule is 12 to 50, and 2
A positive photoresist composition comprising: a low molecular compound having ~8 phenolic hydroxyl groups. However, the molecular weight of the novolac resin refers to a value obtained by gel permeation chromatography using standard polystyrene as a reference value.